1. Field of the Invention
The present invention relates to standardizing the manufacture above-the-knee (AK) and below-the-knee (BK) prosthetic sockets and attached hardware. Specifically, the invention is related to the automation of the alignment jig used in the production of prosthetic devices, which incorporates sensors able translate jig settings into digital records that can be stored and, subsequently transferred to central fabrication facilities for the streamlined and low cost production of the prosthetic devices from the digital records.
2. Description of Prior Art
U.S. Pat. No. 5,926,883, issued to Ulrick A. Veith and Will W. Veith on Jul. 27, 1999, present FABRICATING ASSEMBLY AND CASTING APPARATUS FOR PROSTHETIC AND ORTHOTIC DEVICES, wherein a fabrication assembly for the manufacture of prosthetic and orthotic devices allows various components to be aligned on a common vertical mast with respect to height, distance and rotation alignment criteria.
Various parts and components for vertical jigs, some displayed in this patent application, can be found in Hosmer Tools and Fabrication Supplies Vertical Fabricating Instrument; Hosmer Tools and Fabrication Supplies Component Parts; Hosmer Tools and Fabrication Supplies Fabrication Fixtures; Hosmer Tools and Fabrication Supplies Brim Adaptor and Adjustable Brims; Hosmer Tools and Fabrication Supplies Vertical B & B Universal Casting Fixture. Similar equipment can be found in Fillauer Manuals and Brochures, and literature from other jig manufacturers and vendors. None of these, however, contain the features that will become apparent in this patent application. The innovation relates to the modification and augmentation of existing jig concepts, tools and components, with the creation of a new jig concept which contains internal sensors and actuating devices that significantly enhance the productivity of the jig.
Conventional production of above-the-knee (AK) and below-the-knee (BK) prosthetic sockets and attached hardware entails mounting various components on an apparatus like the Hosmer VFJ-100 Vertical Fabricating Jig, to provide proper alignment of the various parts that make up a prosthetic device. A prosthetic device may include the socket which fits the amputee's truncated limb, the attachment plate rigidly fixed to the socket, a pylon which connects the socket's attachment plate to an articulating or fixed ankle and/or the artificial foot. The pylon is essentially a linear structure, often a cylindrical pipe, with associate hardware for connecting the socket to the ankle or foot.
An important aspect of properly fitting the prosthetic device to the patient is the appropriate placement of the socket attachment plate to the socket, the orientation of the pylon to the attachment plate, and finally the orientation of the pylon to the ankle or foot. The alignment jig plays an important role in physically securing all of the parts, with proper orientation, during the manufacturing process.
During this process, the prosthetist, the professional clinician who fits the prosthetic device to the patient, or a technician under his or her direction, is able to secure and adjust the orientation of the component parts relative to each other on the jig. The jig has various fixtures such as clamps that can secure the parts, with flexible joints that can extend, contract and rotate the component parts to align them according to the prosthetist's judgment of best fit. As will be seen in the following descriptions, there are many degrees of freedom for setting the orientation of the parts relative to each other.
Once the alignment for best fit is achieved, the various clamps can be “locked down,” meaning the clamps and joints can be secured in a fixed position, allowing the technician to remove the component parts from the jig for further processing. The jig, however, retains the settings of“best fit” until the component parts are returned to the jig for final processing and alignment. This is an advantage in that the settings are retained, but also a disadvantage in that the jig is not able to be used by others until the prosthesis is returned to the jig for final adjustments.
Currently, production of trans-tibial and trans-femoral prosthetic sockets starts with the creation of a cast of the patient's residual limb using plaster of Paris wraps or bandages to map the shape of the residual limb. After the wrap has hardened, it is carefully removed and is used as a mold for the casting of a positive plaster mold, a replica of the residual limb, with a pipe embedded in the mold in the axial direction to facilitate handling. After the mold has set, the plaster wrap or bandage is removed.
Alternatively, instead of casting a positive plaster replica of the limb in the hardened plaster wrap or bandage taken from the patient, some fabrication facilities create a digitized solid model computer file by scanning the inside of the patient's plaster wrap with a mechanical sensor or laser scanner. This digitized image can then be modified by computer software designed for this purpose to dimensionally add or subtract “material” from the digitized image in a manner similar to that of a prosthetist adding or shaving material off the plaster cast to adjust or fine tune the cast to better replicate the truncated limb.
Once the Computer Aided Design (CAD) file is generated, it can then be loaded into computer controlled CNC machine tool often referred to as a “carver”, which cuts out a replica of the residual limb in a rigid but malleable material like a high density polymeric foam or wax. At this point, like the process described above for a plaster cast, a thermoforming material is drawn over the positive mold making a negative replica of the limb. This thermoform or thermoset material can be used as a preliminary “check socket” to assess how the well the socket fits the patient.
Prior to the formation of the complete prosthesis, whether from a plaster or high density foam mold, an attachment or adaptor plate is adhered to the bottom or distal end of the thermoset covered mold using an adhesive or harden able putty such as Bondo to secure the plate to the mold, and fill in voids around the plate and the thermoset covered mold. This plate is used to secure the pylon which is essentially a pipe that secures the prosthetic foot to the socket that is fitted to the residual limb. The mold is then used a mandrel for the physical layup of graphite or other high strength cloth, which is then impregnated with resin to form a rigid socket.
Most state-of-art facilities use the above methods for “digitizing” or obtaining a digital record of the shape of the truncated limb in a the form of a CAD file. What is missing, however, in order to fully characterize the prosthesis, are the parameters below the distal end of the socket related to the location and the orientation of the attachment plate on the socket, the orientation of the pylon relative to the attachment plate, and at the junction of the pylon and the ankle, the orientation of the pylon to the ankle.
In the junction of the attachment plate and the upper end of the pylon, there are adaptors that can change the angles or orientation of the pylon relative to the socket by mean of set screws that can be manipulated by the prosthetist to obtain a “best fit.” Also at the distal end of the pylon there are adaptors that can change the angle or orientation of the pylon relative to the plane of the ankle attachment.
This adjustable link, the so called pyramid adapter, was patented by Otto Bock in 1969 and is used worldwide. The adapter consists of two pairs of set screws surrounding a pyramid, allowing adjustment, within a limited swing angle, in two planes. Double, eccentric and sliding adapters offer even more options. Tube adapters and tube clamps add the option of varying lengths and diameters and create an easy-to-adjust connection. The various lamination anchors, socket adapters and socket attachment blocks and provide the transition to the distal component unit. The pyramid adapters are relatively limited in the range of angles they are able to secure.
All of these settings, beyond the CAD file of the truncated limb, become key parameters in determining the final configuration of the prosthesis from socket to ankle. The object of this invention is to use an alignment jig, instrumented with linear and angular micro-encoders, to produce a fully digitized representation of the complete prosthesis, which can be used as a “prescription”, much like that of an eye glass prescription, to allow a Central Fab to produce the full prosthesis using only the digital record.
The conventional vertical alignment jig like the Hosmer VFJ-100 is composed of the following parts;
1. Vertical Column Assembly—                This is a stout cylindrical pipe with a plate or pipe grip at the bottom which allows it to be bolted or otherwise secured to the surface of a workbench. The vertical column can be aligned with a plumb bob attachment that allows the technician to precisely orient the column in the vertical or “z” direction. This vertical column can support clamp assemblies that contain horizontal shafts with fixtures at the end of each shaft that hold and align components of the prosthesis being integrated on the jig. At the back of the vertical column is a slot running the full length of the column into which a slot key on each clamp can be inserted to align the clamp on the column in a fixed position. All of the clamp assemblies can be raised and lowered on the vertical column, with a rotatable knob on each clamp that that can be tightened to “lock down” and secure the clamp to the column. A slide able collar can be positioned under the clamp assembly and tightened to allow the knob on the clamp assembly to be loosened so the assembly can be rotated in the horizontal plane and maintain a constant level in the “Z” or vertical direction.        
2. Horizontal Shaft Assemblies—                Each of the clamps cited above can accommodate and orthogonal horizontal shaft which can be extended, contracted, and rotated in the clamp fixture, with the whole assembly able to be rotated about the vertical column in the horizontal or “X-Y” plane. There are two knobs on each clamp. One locks down the shaft to the clamp assembly, and the second, the clamp assembly to the vertical column. Like the vertical column, each shaft on its top side has slots running the length of the shaft where slot keys can be inserted secure the shaft in a fixed position if so desired.        
3. Upper Clamp Assembly—                This is a fixture referred to in the Hosmer literature as the Mandrel Holding Assembly. This Upper Clamp Assembly has a fitting at the end of the shaft that allows a plaster cast to be held vertically by mans of a pipe embedded in a plaster mold (areplica, or mandrel, of the patient's truncated limb) held in place by a fixture at the end of the shaft known as a Mandrel Bushing.        
4. Middle Clamp Assembly—                This is a fixture referred to in the Hosmer literature as the Knee Holding Assembly. This assembly can have yoke-shaped fixture at the end of the horizontal shaft which allows the technician to clamp and hold larger objects like a check socket which is a thermoplastic replicas of the truncated limb. This yoke apparatus has four bolts in the semicircular yoke frame that can be tightened down to secure the object in the yoke.        
5. Lower Clamp Assembly—                This is a fixture referred to in the Hosmer literature as the Ankle Holding Assembly. The horizontal shaft has a fixture on its end with a horizontal plate that can be moved side to side in the X-Y plane by a screw mechanism. This plate can hold the attachment mechanism for pylon to the ankle or foot.        
As one can see, there are numerous degrees of freedom built in to the convention alignment jig, with clamp assemblies able to be raised and lowered on the vertical column in the “Z” direction, and rotated about the vertical column in the “X-Y” plane. Furthermore, horizontal shafts with fixtures on the ends can be, extended, contracted, and rotated within each clamp assembly. The fixtures themselves can have internal degrees of freedom, such as the positioning of objects in the yoke in the Middle Clamp Assembly, and the positioning of the pylon-ankle attachment in the Lower Clamp Assembly.
Beyond the extensions and rotations described above, there are other minor angular adjustments that can be made at specific sites using what are known as single and dual pyramid adaptors. In these adaptors, the relative angles of male and female adaptor plates, within a few degrees of rotation, can be adjusted with four screws in the female component tightened against sloping sides of the male pyramid component. These pyramid adaptors can be found at the socket and ankle ends of the pylon as well as at the end of the Upper Clamp Assembly shaft when coupled with a rotatable joint affixed to the Mandrel Bushing.
Once the technician has assembled the various components on the jig, aligned them, and locked down all of the setting, the jig itself stores the settings while the technician continues on to the production of the prosthesis. The jig now unable to be used for other production until the technician has finished the original prosthesis. Furthermore, once the jig is used for production of a different prosthesis, the original settings are essentially lost. If another duplicate socket is required at a later date, the process must be repeated from scratch, requiring new settings to be generated.
This invention relates to the recording and reproduction of major settings related to the alignment of the prosthesis, allowing the prosthetist flexibility to make minor adjustments by means of the single and dual pyramid adaptors described above.